This invention relates to an automatic working method and an automatic working machine and more particularly to an automatic arc welding method and machine which are suitable for a welding robot.
In recent years, the shape and the welding path of a work piece (an object to be welded) have been practiced in great variety and the advent of an automatic welder having capability to meet such a variety of needs has been desired.
A prior art welder designed to comply with such various needs is disclosed in, for example, "Program for Flat Fillet Welding Parameters by CO.sub.2 Arc Welding,"Papers of the Japan Welding Society, Vol. 4, No. 1, 1986. This paper reports algorithm for automatically deriving welding conditions applicable to a narrow restricted area alone. This prior art welder can however be applied only to the specified type of welding or flat fillet welding. Further, this prior art welder is designed to take a predetermined installation direction, that is, forced to face a predetermined direction when installed. Accordingly, this prior art can not sufficiently meet the aforementioned needs.
In electric arc welding, molten metal forms a pool and the pool is cooled so as to be solidified into a bead by which base metals can be jointed together.
It is therefore clear that the condition (shape, size, temperature and the like) of the pool of molten metal appearing in this phase greatly affects the quality of welding.
More specifically, the pool is naturally a liquid pool affected by gravity and its shape varies depending on a direction of the pool surface relative to the direction of gravity or the direction in which the gravity exerts its influence. Under the circumstances, if the welding condition is improper, the molten metal will collapse to flow out, giving rise to defective welding.
The previously-described prior art fails to take the influence of gravity into consideration and has difficulties in insuring welding qualities when complying with a variety of work piece shapes and welding paths.
The above situation is seen in the field of sealing robots as well. Sealing robots are those having a nozzle fixed to an arm thereof for sealing a joint by feeding to the nozzle a sealing material bit by bit. In this field as well, there is seen a great demand for a more versatile sealing robot.